Can ESFR Protect Extra Hazard Operations?

8/19/2025

Can an ESFR system protect extra hazard occupancies such as plastic injection molding operation using combustible hydraulic fluid?

If not, what is the concern?

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5 Comments

Pete H

8/19/2025 06:22:28 am

https://www.meyerfire.com/daily/can-esfr-be-used-for-extra-hazard-group-2

This older thread had a bit of this discussion.

The short answer is "no".

The long answer is "Unless the ESFR sprinkler is listed for extra hazard occupancies, it is not suitable to protect them. ESFR sprinkler design is for a few sprinklers to go off to contain a storage fire with open shelving. The square footage required for an extra hazard potential fire as well as the processes within an extra hazard space are not considerations in an ESFR design. Light and Ordinary hazard were allowed so warehouses could be retrofitted to offices with minimal modification."

Jesse

8/19/2025 08:13:26 am

No, I'm afraid not.

ESFR is all about volume which is why we refer to ESFR as "suppression mode" vs. control mode. Because its designed to put a fire out, it uses a lot of water. And as such, has the potential to overwhelm the water suppy in some circumstances. High piled storage has a lot of stored energy. However, whereas there is a lot of BTU release in a storage fireeeee, its generally a slower release rate.

Extra Hazard occupanices also invovle a lot of potential energy, but the release rate is dgenerally way faster. Think flashy fire. The quicker energy release has the potential to open too many ESFR sprinklers - which has the potential to overwhelm the water supply.

Mike

8/19/2025 09:17:03 am

Per NPFA 30 Annex A16.1.1 Early suppression fast-response (ESFR) sprinklers have been tested for protection of liquids only to the extent reflected in the tables in Section 16.5. of NFPA 30. Any other use of ESFR sprinklers for protection of liquids should be based on an engineering analysis that evaluates the potential failure of the sprinkler system based on a rapid-growth fire or a large pool fire that would operate more sprinklers than are accommodated by the design area. The use of ESFR protection, particularly without provisions for the control of spread of liquid, presents the possibility of a liquid pool fire that could exceed the limited design operating area of an ESFR system. You can follow FM data sheet 7-98 for protection of hydraulic use areas.

Franck

8/19/2025 10:19:02 am

It might work, but there are too many uncertainties and as indicated above, if for some reasons you quickly open too many ESFR because of an oil spray from the hydraulic unit, you may overtax your system and the fire will not be controlled ending with huge fire, smoke and water damages

Storage sprinklers are to be used for storage occupancy and not for process areas.

Pete D

8/20/2025 06:08:20 am

I'm taking a contrarian position. FM lists sprinklers as storage and non-storage. Many UL listed ESFR sprinklers are also listed by FM as storage sprinklers. When a FMDS provides a protection strategy table with orifice and pressure, it's not different than a CMDA strategy, understanding these tables will either say QR or SR, and ESFR sprinklers are cross listed as quick response. The problem is the standard ESFR design area is only 1,200 sq.ft. and EH 1 & 2 begin at 2,500. I have a site with a 3,500 gpm pump that protects rolled paper. It has ESFR K-14 @75 psi with 25 sprinklers in the design area. My points are: 1) depends on the water supply more than the sprinkler. 2) are we talking about life safety or loss prevention? the nuanced technical answer or the risk matrix? If it's the risk matrix, I'd conduct EH operations all day long under (25) k-14 @ 75 without losing a wink of sleep.

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Can ESFR Protect Extra Hazard Operations?

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